Electrical apparatus



Sept. 14 1926.

v G. A. BURNHAM ELECTRICAL APPARATU@ Filed April 29, 1924 3 Sheets-Sheet l sept. 14, 1926.

G. A. BURNHAM ELECTRICAL APPARATUS Filed April 29. 1924 Sept. 14 1926. 1,599,644

G. A. BURNHAM ELECTRICAL APPARATUS Filed April 2 9, 1924 3 SheetS-Sheet 3 Patented Sept. 14, 1926.

` UNITED ySTATI-:s

g 1,599,644 PATENTOFFICE.

GEORGE A. nURNHAir, or` sAUGUis, MASSACHUSETTS, AssIGNOR, RY MEsNE A'ssIGfN- MENTS, TO CoNmT ELECTRICAL MANUFACTURING CORPORATION, OE RosTON;` MASSACHUSETTS, A CORPORATION or MASSACHUSETTS.

ELECTRICAL APPARATUS.

Application llled April 29,1924. Serial No. 709,922. y

This invention relates to oil immersed electrical apparatus, as electric switches. and switching stations and systems. Y.

lVhen an Oil immersed switch is opened 'under heavy load, oil vapors and gases are or may be generated within the switchy casing and under certain conditions explode and thereby impose severed stresses upon, if not actually damage to the switch structure.

An Aobject of this invention is the provision of an Oil immersed electric switch with an expansion chamber, the internal volume of which is relatively great as compared with the internal volume of the switch casing, whereby to keep down the internal pressures within the switch.

A further Object ofthe invention is the provision of a switch having an open top enclosing casing adapted to contain the arcquenching fluid in the -bottom thereof and switch-members extended through the casu ing below the open top, the top-opening being at suoli` a distance above the fluid level 'in the casing as to retain such amounts of fluid that may be moved upwardly aboye the normal fluid level during circuit-interrultion. l Y I further object is to provide means insuring the natural and substantially continual ventilation of the switch whereby to maintain it free from anI explosive mixture. A further object is to provide in one structure means for carrying out the Vabove f enumerated objects of this invention.

A'further object of the invention is generally to improve "the construction and operation ,o electric switches.

1 is a sectional elevation through a switching station containing the invention. Fig. 2 is a sectional detail along lines 2-'2 of Fig.

-F Fig. 3 is'a plan detail along lines 3 3 of 4 is a sectional elevation through one of the switch units of Fig. 1 and taken alonglines 4-4 of Fig. 1. v

Fig'. 5 is a vertical sectional detail taken along lines 5,-5 of Fig. 4.

Fig. 6 is a view of an outdoor-type electric switch embodying the invention associated with a transmission line.

` Fig. 7 is -an elevation of the switch of Fig. s.

Fig. 8 is 'a vertical sectional elevation of the switch of Fig. 6.

Figs. 6, 7 and 8 illustrate .certain features .of thefinvention. The switch lincludesI a casing having the switcli frame 10 which preferably -is more Or less circular.A Said frame 10 is formed with an upper neck 11 which forms a venting passage for the escape of oil gases and vapors from the switch. Said switch frame 10 is formed, also, with a lower opening 12 preferably disposed below and in vertical line with-the neck opening 1.1. An oil-receptacle 13,` referably cylindrical, is received in said ower opening.

12. Said oil receptacle may be secured to the switch frame 10 by suitable means as the tieyrods 14; and said receptacle may be removed from the casing by removing the nuts 15 from the ends of said tie rods. aryswitch members 16 are secured to the switch frame 10 on opposite sides of the neck-opening l1 and extend angularly through said switch frame and into the oil in said receptacle.

Station- A movable switch memf ber 17 cooperates with said stationary switch members-to control the circuit'througll the *switch The switch frame 10 is or may be formed or provided with supporting brackets 20, which brackets are disposed on opposite sides of'theswitch frame and extendl Saidv brackets serve to .support the switch in elevated position upon a.l suitable supportingl structure 21 andpreferably in such an ele-.-

outwardly beyond the oil receptacle.

vated position thereon that the Oil receptacle may be lowered to clear the stationary and movable switch members for the removal of the receptacle from the switch. The switch herein shown is of the outdoor typefand in Fig. 6 is interposed between and connected to the conductors 23 and 24 of a transmission lirie although, obviously, 'the switchmay be otherwise arranged.-

It is an object of this invention to make the neck-opening 11 of the switch-frame as large in cross sectional area as is commercially practicable and, as is here shown most clearly in Fig. 8, the neck opening is approximately equal in crow sectional area to that of the Oil receptacle 13. A conduit 26 is secured to the neck of the switch frame and about the neck Openin therein and extends vertically upward or a substantial distance, say'upwards of ten feet. Said conduit is preferably of uniform diameter and is open at its upper end. -A rain shield 27 may be secured over the open upper end of said conduit and serve to 'prevent rain and snow from entering the conduit although not to restrict free and unrestricted communication between said conduit and the atmosphere. As thus arranged, it is apparent that said conduit 26 may function as an exceedingly large expansion chamber for the switchA as the volume in said conduit is many times larger than the volume of the switch casing comprising the switch frame 10 and that portion of the oil receptacle above the oil s level therein. Due to the large internal dimensions of the conduit, internal pressures set up in the switch casing due to generation of oil gases and vapors therein may be kept down to arelatively low value. Since thc conduit 26 is of substantially uniform crosssect-ion throughout its'length and is freely open at the top, thev switch may vent with the greatest rapidity whereby to keep down internal pressures.

The conduit 26 also functions as a chimney to ventilate the switch automatically and continually. Due to the fact that the temperature of the switch, when carrying current, is, ordinarily, elevated above that of the atmosphere, the Vgaseous contents of the switch become heated and tend to rise therethe mixture is not explosive.

due to the natural draft set up by the conby setting up a draft along the vertical height of the chimney. The oil receptacle 13, while it may be in close contact with the switch frame 10", need not ordinarily have an air tight connection therewith and consequently, due to the thermal circulation of the gases along the length of the conduit 26, fresh air may be continually drawn into the switch casing whereby to sweep out any oil vapors and gases that may collect therein and maintain the switch casing and the air conduit filled with substantially pure air or at leastfwith a mixture containing such a low proportion of oil vapor and gases that If desired, I may specificallyprovide openings for the entrance of fresh air into the switch. One of such openings, as the opening 30, is shown in Figs. 7 and 8 and said opening may be governed by a swinging valve 31. Said valve may be so arranged that it will open duit 26 and admit fresh air into the switch casing and conduit but when any substantial pressure is set up within the switch casing, the valve is adapted to close whereby to prevent the escape of gases and oil through the opening. When specific openings for the admission of air in the switch casing and conduit are provided, it is obvious that the joint between the oil receptacle and switch frame may be made gas tight.

' The vent openings 30 may be eliminatedif switch unit installed within aswitching station. Y The construction of a switching unit is illustrated best in Fig. 4. The switch unitis provided with a switcli frame 40 and carries the three sets of stationary switch members 41, 42 and 43. Said switch frame 40 `is 'formed with lower openings 44 in which the l oil receptacles 45 are received and the oil receptacles ma be secured to the switch frame, prefera ly removably, in any suitable manner.

The receptacles may be provided with wheels 46 whereby each independent receptacle ,may be moved about free from the switch or the entire switch as as a unit may bepmoved about.

The switch frame is designed to have an internal cross sectional area which is approximatelyas large as the cross Sectional area of each oil receptacle, and all receptacles are in open communication with the interior of the switch frame. The switch frame is formed or provided with the necks 5() which necks are disposed at the upper portion of the switch frame and between the stationary switch members. The neck openings 50 are adapted to be as large as practicable, as set forth in connection with the construction of switch illustrated in Figs. 6, 7 and 8.

Fig. 1 shows a switching station equipped with two of the switch units above described. The switch units may be contained in the separate arms or compartments a and connected to circuit leads b. Circuit leads c may extend from the other poles of the switch and pass'through partition walls d to Ydisiconnecting switches e. Circuit leads f ma pass from t-he disconnecting switches throng i the wall g and into bus compartments IL and be connected with busses 'i in said compartments. Each switch unit may be provided with two combined expansion chambers and Ventilating chimneys 55, which chimneys are connected to the necks 50 of the switch units. Said chimncys'55 are disposed between the stationary switch members of the switch units and between the circuit leads connected thereto as is clearly shown in Figs. 2 and 3. Said chimneys Aextend vertically upward from the switch unit and preferably are secured permanently in positlon in the lll..

station. Said chimneys may extend through the upper door of the station contalning t e bus compartments and pass through the rpof j of the station and open into the atmosphere above the` roof. The function of said chimneys 55 are identical with the conduits 26 and set forth in connection with the con-` struction illustrated in` Figs. 6, 7 and 8. The switch frame may be provided with a draft inlet opening 30* and a swinging valve 31 may be arranged to coverA said opening to prevent the discharge of gases outwardly through the opening and swing away from the opening to permit the natural ventilation draft increasing means actuated by lateral air currents circulating about theo en upper ends of the conduits. Said draft increasing means may include a head 60 illustrated in connection with the right hand switching apparatus hown in Fig. 1. Said head is freely pivo edj on and about the upper end4 of the right hand chimney 55 andy is provided with a vane 61 to maintain it in line with the moving air currents. A draft nozzle 62 may becarried by said head and be in free and unimpeded communication with said said nozzle. An induction nozzle 63 may be axiall disposed in respect to and open into raft nozzle 62. The passage of air through said induction nozzle 63 into the draft nozzle serves to set up a forced draft in the chimney thereby to enhance thenatv ural draft thereof.

The chimney 55 and also the conduit 26 l (may be made of any suitable material as encuit interruption ma tirely of metal or entirely of some insulatingmaterial, or, if desired, the lower ends of said conduits may be made of insulating material in an obvious manner, and the upper ends may be made of metal.

With the construction herein shown thel circuit interru tion takes, place, in effect, at the bottom o a relatively tall chimney, which chimney offers free escape for the arc gases formed. Oil displaced during'the cirbe thrown upwardly to a substantial heli t within the chimney but will again fall downwardly and be returned to the switch while the oil gasesand vapors will be separated vfrom the displaced oil and eventually'be discharged into theatmosphere through the open-upper end of the chimney and out of proximity `with live conductors.

The construction may be otherwise modified without departing lfrom the spirit of the invention.

I claim: 1. An electrical apparatushaving a casing adapted to contain a vaporizable fluid, nd a gas expansion space above the fluid, and agas-expansion chamber connected with said casing and in free communication with said gas expansion space, said as-expansion chamber havin approximat y the crosssectional area o? the casing and a volume at least as great as the volume of said gas expansion space.

2. An electrical apparatus having a casing gas-expansion chamber connected with said vcasing and in free communication therewith,

said gas-expansion chamber having approxi'- mately the cross-sectional area of the casing and a volume at least as great as the volume of said casing and having a' free vent-opening over approximately its entire cross-sec.

tion.

3. An electric switch having an enclosing casing adapted to contain an' arc-quenching fluid, and a gas expansion space above the fluid, and a gas-expansion chamber connected with said casing and in free communication 'with said as expansion space, said chamber comprising aconduit of substantial length extended approximately vertically:

above said switch casing and having transverse dimensions comparable with the transverse dimensions of the switch casing. 4. An electric switch comprising the combination lof an approximately vertical con. 4duit closed at its lower end and freely open vat its upper end having a hei ht which imensions, and having a large and approximately unigreatly exceeds its transverse form cross-section throughout its height, and ada ted to contain a body of arc-quenching lui in its closed end, and stationary an 'adapted to contain a vaporizablefluid, and a movable switch members containedY in the in the bottom thereof, and stationllO ary and movable switch members immersed in the fluid;

7. Anelectric 'switch having a casin adapted to contain an arc-quenching iui and means including a chimney arranged in ing to provide for a natural ventilation of the casing.

8. An electric apparatus having a casing adapted to contain a vaporizable fluid, an

communication with the interior of the vcasmeans to provide fora natural ventilation of ,the casing including a chimney with the interior of said casing and extended to a substantial height thereabove, said casing having means for the entrance of air therein above the fluid level.

9. An elect-ric switch having a casing adapted to contain an arc-quenching fluid, and means to provide for a natural ventilation of the casingE including a chimney in free communication with the interior of said Casing and extended to a substantial height thereabove, said casing having an air-inlet opening above the oil level in the casing, and means governed by pressure conditions within the casing arranged to close said opening.

10. An electric switch having a casing adapted to contain an arc-quenching fluid, and means to providea natural ventilation for the switch including a chimney connected'with the interior of said casing and ei;- tended upwardly theleabove and having its upper end freely open to the atmosphere, and draft-increasing means associated with the chimney to enhance the natural draft thereof.

11. An electric switch having a casino'v the switch including a chimney connectedv with the interior of said casing and extended upwardly thereabove and having its upper end freely open to the atmosphere, and means to enhance the natural ventilation provided by said chimney including a suction apparatus disposed at the upper end of and in operative communication with the interior of said chimney.

1Q.. An electric switch having an enclosing casing and means to ventilate the casing including a relatively large and tall chimney having its lower end arranged in free communication with said casing and its upper end freely open to the atmosphere, and thermal means including current-carrying com ponente of the switch to establish displacement of gas upwardly in said chimney.

13. An elect-ric switch having an enclosing casing and means to ventilate the casing including a relatively large and tall chimney having its lower end in free communication with said casing and its upper end 'freely openy to the atmosphere and electric heating means including current-carrying components of the switch to establish a displacement of gas upwardly within saidv chimney. s

14. An electric switch having an enclos- .ing casing and means to ventilate the cas- .ing including a relatively large and tall v'chimney having its lower end in free communication with said casing and its upper end freely open to the atmosphere Jand electric heating means including current-conducting components of the switch to establish a displacement of gas upwardly within said chimney. l

15. An electric switching station having a chimney extended upwardly and freely open to the atmosphere, and an electric switch having an enclosing casing connected with said chimney.

16. The combination of a fixed chimney, a movable electric apparatus having a casing arranged for communication with said chimney, and means removably/to secure said casing in communication with said chimney.

1T. The combination of a fixed chimney, an oil receptacle disposed at the lower end of the chimney, means to secure .said receptacle removably in position, and switch members extended into said receptacle.

1'8. An electric switching station including a chimney having an open lower end and having its upper end open into the atmosphere, and an electric switch having a casing arranged in communication with the open lower end of the chimney.

19. An electric switching station having `a lower switch-room, an upper bus-room, a chimney extended through both rooms and having a lower opening into the switchroom and having its upper end freely open to the atmosphere, an electric switch contained in the switch room, said switch having a casing secured in communication with the'open lower end of said chimney, and circuit leads extended on opposite sides of the chimney between the switch and the bus room.

20. An electric vswitch having a casing adapted to contain an arc-quenching fluid in the bottom thereof, said casing having a top-opening which is approximately co-extensive with the cross-section of the casing, and switch-members extended through said casing below the open top.

21. An electric switch having an open-top casing adapted to contain an arc-quenching fluid in the bottom thereof, vthe open top being of such size as to vent the switch rapidly, and the height of the casing above normal fluid level therein being such as to retain fluid thrown upwardly above the normal fluid level during circuit interruption under any load which leaves theswitch in condition to be reclosed immediately and carry the normal load on the switch.l

In testimony whereof, I have signed my name to this specification.

GEORGE A. BURNHAM. 

